System and method for coordinating device-to-device communications

ABSTRACT

A master user equipment (UE) device may coordinate device-to-device (D2D) communications amongst a plurality of UE devices. For example, a UE device, which has been designated as a master UE device, may coordinate a D2D communication between a first UE device and a second UE device. The master UE device may be a UE device that obtains an indication that it is a master UE device that is to coordinate D2D communications amongst the plurality of UE devices. In some embodiments, the coordinating the D2D communication may be on behalf of a network and/or to facilitate wireless communication between the network and at least one of the plurality of UE devices.

RELATED APPLICATION

This is a continuation of U.S. patent application Ser. No. 14/609,644,which was filed on Jan. 30, 2015, which is entitled “System and Methodfor Coordinating Device-to-Device Communications”, and which isincorporated herein by reference.

FIELD

The following relates to coordinating device-to-device communicationsamongst a plurality of devices.

BACKGROUND

In a traditional mobile network, all communication between userequipment (UE) devices goes through a base station, even if two UEdevices communicating with each other are in close physical proximity.

Device-to-device (D2D) communication has more recently been introducedto allow for UE devices in close physical proximity to directlycommunicate with each other without using the base station.

As the number of UE devices in a mobile network increases, there may bemore potential opportunities for D2D communication.

SUMMARY

Embodiments are described in which a master UE device may coordinate D2Dcommunications amongst a plurality of UE devices.

The master UE device may be a UE device of the plurality of UE devicesthat obtains an indication that it is to be a master UE device. Themaster UE device may then coordinate a D2D communication between a firstUE device and a second UE device. This may be done by transmitting aninstruction to at least the first UE device to coordinate the D2Dcommunication.

Coordinating D2D communications between UE devices may involveorganizing and/or controlling the D2D communications. For example, thecoordinating may comprise instructing two UE devices to perform a D2Dcommunication. As another example, the coordinating may comprisecontrolling use of the wireless channel for a D2D communication betweentwo UE devices to mitigate interference with D2D communications of otherUE devices. As another example, the coordinating may comprisedetermining and/or instructing one or more UE devices to be a “helper”to use D2D communication with one or more “target” UE devices in orderto assist with wireless communication between a network and the one ormore target UE devices.

In another embodiment, a UE device is provided which may includeprocessing circuitry configured to implement a D2D coordinator. The D2Dcoordinator may coordinate the D2D communications. The UE device mayinclude other hardware also, for example, at least one antenna tocommunicate with a network, and to communicate with other UE devicesusing D2D communication.

BRIEF DESCRIPTION

Embodiments of the present application will be described, by way ofexample only, with reference to the accompanying figures wherein:

FIG. 1 shows an example of a telecommunications network in accordancewith one embodiment;

FIG. 2 shows an example of a D2D group of UE devices from the embodimentillustrated in FIG. 1:

FIG. 3 shows an example of operations performed by a D2D coordinator inaccordance with one embodiment;

FIG. 4 shows an example of different target/helper UE devicecombinations in accordance with one embodiment;

FIG. 5 shows an example of controlling use of the wireless channel forthe D2D communications in accordance with one embodiment;

FIG. 6 shows an example of a “decode-and-forward” operation inaccordance with one embodiment;

FIG. 7 shows an example of aggregating uplink signaling in accordancewith one embodiment;

FIG. 8 shows an example of a UE device acting as a proxy for other UEdevices in accordance with one embodiment;

FIG. 9 shows an example of operations that may be performed by thenetwork in accordance with one embodiment;

FIG. 10 shows an example method of establishing a master UE device inaccordance with one embodiment;

FIG. 11 shows an example method of establishing a master UE device inaccordance with another embodiment;

FIG. 12 shows an example method of establishing a master UE device inaccordance with another embodiment;

FIG. 13 shows an example of an access network and UE device inaccordance with one embodiment; and

FIG. 14 shows an example method performed by a UE device in accordancewith one embodiment.

Like reference numerals are used in different figures to denote similarelements.

DETAILED DESCRIPTION

For illustrative purposes, specific example embodiments will now beexplained in greater detail below in conjunction with the figures.

The embodiments set forth herein represent information sufficient topractice the claimed subject matter and illustrate the best way ofpracticing such subject matter. Upon reading the following descriptionin light of the accompanying figures, those of sufficient skill willunderstand the concepts of the claimed subject matter and will recognizeapplications of these concepts not particularly addressed herein. Itshould be understood that these concepts and applications fall withinthe scope of the disclosure and the accompanying claims.

Moreover, it will be appreciated that any module, component, or deviceexemplified herein that executes instructions may include or otherwisehave access to a non-transitory computer/processor readable storagemedium or media for storage of information, such as computer/processorreadable instructions, data structures, program modules, and/or otherdata. A non-exhaustive list of examples of non-transitorycomputer/processor readable storage media includes magnetic cassettes,magnetic tape, magnetic disk storage or other magnetic storage devices,optical disks such as compact disc read-only memory (CD-ROM), digitalvideo discs or digital versatile disc (i.e. DVDs), Blu-ray Disc™, orother optical storage, volatile and non-volatile, removable andnon-removable media implemented in any method or technology,random-access memory (RAM), read-only memory (ROM), electricallyerasable programmable read-only memory (EEPROM), flash memory or othermemory technology. Any such non-transitory computer/processor storagemedia may be part of a device or accessible or connectable thereto. Anyapplication or module herein described may be implemented usingcomputer/processor readable/executable instructions that may be storedor otherwise held by such non-transitory computer/processor readablestorage media.

Turning now to the figures, some specific example embodiments will bedescribed.

Establishment of a Master UE Device:

When multiple UE devices are performing D2D communications, there may bea lack of coordination between the UE devices. For example, there may beno process (or no efficient distributed process) for controllingwireless channel access for the D2D communications amongst the UEdevices to try to prevent interference between the D2D communications.In particular, a carrier sensing multiple access process, or somethingsimilar, which may be employed by the UE devices on an ad hoc basis totransmit the D2D communications, may not provide adequate quality ofservice (QoS) or scale well as the number of UE devices participating inthe D2D group grows. In some cases, the ad hoc D2D communicationsbetween the UE devices may result in conflicts or collisions, resultingin less effective or ineffective D2D cooperation between the pluralityof UE devices, due to the lack of coordination. As another example, ifthe UE devices are working together in a cooperative D2D group tocommunicate with a network, there may be no process for facilitatingcommunication between the network and the D2D group. For example, theremay be no process for determining which (if any) UE devices are to be“helpers” and which (if any) UE devices are to be “targets”, where ahelper uses D2D communication with a target to assist in a wirelesscommunication between the network and the target.

In view of this, a “master” UE device may be established to coordinatethe D2D communications between the UE devices. Examples relating to theestablishment and role of the master UE device will be explained belowin the context of specific embodiments.

Example of a Telecommunications Network and a Master UE Device:

FIG. 1 shows an example of a telecommunications network 100 inaccordance with one embodiment. The telecommunications network 100includes a core network 102 and a radio access network 106. The corenetwork 102 is the central part of the telecommunications network 100and provides various services, such as (for example) callcontrol/switching and gateways to other networks. The core network 102comprises network components such as routers, switches, and servers.

Connected or coupled to the core network 102 is the radio access network106, which in the illustrated embodiment is a cloud radio access network(C-RAN). A C-RAN is sometimes also referred to as a Centralized-RAN. UEdevices 104 a, 104 b, 104 c, 104 d, 104 e, 104 f, 104 g, and 104 h,which also may be referred to as nodes, wirelessly access thetelecommunications network 100 using the radio access network 106. Itwill be appreciated that although a C-RAN is described with respect tothe figures, this is only an example, and the present disclosure is justas applicable in the context of other access networks.

The radio access network 106 includes a plurality of remote radio heads(RRHs), thee of which are illustrated: RRH 108 a, 108 b, and 108 c. Eachone of the RRHs 108 a-c provides a respective wireless coverage area 110a, 110 b, and 110 c. Each RRH 108 a-c may be implemented using a radiotransceiver, one or more antennas, and associated processing circuitry(e.g. antenna RF circuitry, analog-to-digital/digital-to-analogconverters, etc.).

Each RRH 108 a-c is connected to a centralized processing system 110 inthe radio access network 106 via a respective communication link 112 a,112 b, and 112 c. The communication links 112 a-c may each be a fibrecommunication link. Each RRH 108 a-c includes circuitry for transmittingdata to the centralized processing system 110 and for receiving datafrom the centralized processing system 110 via its respectivecommunication link 112 a-c.

The centralized processing system 110 may be implemented by a network ofone or more processing and control servers. Alternatively, thecentralized processing system 110 may comprise a single server. In thecontext of a C-RAN, the centralized processing system 110 may includeone or more baseband units (BBUs), which may perform baseband processingof data for/from the UE devices 104 a-h.

Each of RRH 108 a-c is an example of a base station in that each RRH 108a-c comprises a radio receiver/transmitter that a UE device wirelesslycommunicates with to access the radio access network from within itsrespective wireless coverage area. A base station may serve as thegateway between the wireline and wireless portion of the radio accessnetwork 106, although this need not be the case (e.g. the communicationlinks 112 a-c could be wireless). Base stations may be placed at fixedlocations by the network provider, for example, in a strategic manner toprovide a continuous wireless coverage area. This is shown in FIG. 1 inthat wireless coverage areas 110 a, 110 b, and 110 c overlap each otherso that all of UE devices 104 a-h may move throughout the wirelesscoverage areas 110 a-c, from one wireless coverage area to another, andbe served by the radio access network 106. A base station may also bereferred to as a base transceiver station, a radio base station, anetwork node, a transmit node, a Node B, or an eNode B, depending uponthe implementation.

Although each of RRH 108 a-c is considered to be a base station, it willbe appreciated that the RRHs 108 a-c may have fewer processingcapabilities compared to previous generations of base stations, sincesuch processing capabilities may instead be offloaded to the centralprocessing unit 110, as per the C-RAN architecture.

Each one of the UE devices 104 a-h in FIG. 1 is able to wirelesslycommunicate with an RRH. For example, UE device 104 e can wirelesslycommunicate with RRH 108 a, as shown at 114.

The four UE devices 104 a, 104 b, 104 c, and 104 d are in close physicalproximity to each other. For example, the users of UE devices 104 a-dmay each be attending the same event and situated close to each other,or they may be four friends or family members in the same house or inthe same car. Although the UE devices 104 a-d can each wirelesslycommunicate with the RRH 108 a, they can also directly communicate witheach other using D2D communications 116. A D2D communication is a directcommunication between UE devices that does not go through an accessnetwork component, such a base station. As shown in FIG. 1,communications 116 are directly between the UE devices and are notrouted through the base station, or any other part of the network 106.D2D communications may also sometimes be referred to as lateralcommunications. On the other hand, a communication between an accessnetwork component, such as a base station, and a UE device (e.g.communication 114) is called an “access communication”, which may besaid to occur over an access channel.

The D2D connections between the UE devices 104 a-d may have beenestablished using a discovery process. One example of a discoveryprocess is as follows: each UE device 104 a-d periodically sends out adiscovery message or signal to determine if there are neighbouring UEdevices in physical proximity to set up a D2D communication link. EachUE device 104 a-d also periodically listens for such discovery messages.When a discovery message is received, the D2D communication link betweenthe receiver and the sender can be set up via a predetermined protocol.Another example of a discovery process is as follows: one or more of UEdevices 104 a-d receives a message from the RRH 108 a (originating inthe radio access network 106), the message indicating that there isanother UE device in close physical proximity. Upon receipt of thismessage, the UE device then transmits a discovery message (or listensfor a discovery message) to set up a D2D communication link with theother UE device. Another example discovery process is as follows: thehuman users of the UE devices 104 a-d decide that they want to set upD2D communication links, and therefore come within close physicalproximity to each other and manually instruct their respective UEdevices to set up a D2D communication link. This manual prompt causesthe UE devices to send and/or receive discovery messages to set up theD2D communication links.

Referring to FIG. 1, once the D2D connections are established, the UEdevices 104 a-d may be considered members of a D2D group, forming an adhoc system for directly communicating with each other using D2Dcommunications. As will be appreciated, the D2D coordination methodsdescribed herein are applicable to D2D groups with any number ofdevices, although some of the methods may be more suitable for D2Dgroups that comprise at least three UE devices.

The D2D communications between the UE devices 104 a-d may have a benefitin that the UE devices 104 a-d may assist each other with wirelesscommunications (e.g. transmission(s) and/or reception(s)) between the UEdevices 104 a-d and the RRH 108 a. A D2D group that works together toassist or facilitate communication between members of the D2D group andthe network may sometimes be referred to as a cooperative UE group, asthe D2D group members are cooperating with each other using D2Dcommunications. As a simple example, if UE device 104 c fails tocorrectly decode a packet received from the RRH 108 a, but if UE device104 d is able to receive and correctly decode the packet, then UE device104 d could directly transmit the decoded packet to UE device 104 cusing D2D communication.

In some embodiments, the D2D group may be viewed by the radio accessnetwork 106 as a single virtual entity, called a “virtual userequipment” (VUE).

While FIG. 1 shows that all of the UE devices 104 a-d communicate withthe same base station (RRH 108 a), in general, different ones of the UEdevices 104 a-d may communicate with different base stations. As anexample, if UE device 104 d happened to instead be located in coveragearea 110 b (i.e. the D2D group was spread across coverage areas 110 aand 110 b), then UE device 104 d may directly communicate with RRH 108b, or UE device 104 d may indirectly communicate with RRH 108 a throughother ones of the plurality of UE devices that are within the wirelesscoverage area of RRH 108 a. For example, UE device 104 d may send amessage directly to UE device 104 a using D2D communication, and UEdevice 104 a may then forward that message to RRH 108 a.

As mentioned earlier, a lack of coordination between UE devices in a D2Dgroup may be a problem. In view of this, one of the plurality of UEdevices 104 a-d acts as a master UE device, which in FIG. 1 is UE device104 a, and is designated by the letter “M”. Example ways to establish aparticular UE device as a master UE device are described later. One taskof the master UE device 104 a may be to coordinate the D2D activitiesand communications amongst the plurality of UE devices 104 a-d such thatthere is centralized organization of the UE devices 104 a-d and theirD2D communications. Examples of such coordinating activities aredescribed in detail later.

FIG. 2 shows the UE devices 104 a-d in more detail. The master UE device104 a includes a communication subsystem 150, two antennas 152 and 154,a processor 156, and a memory 158. The master UE device 104 a alsoincludes a D2D coordinator 160 and a D2D participator 161, thefunctionality of which will be explained below.

The communication subsystem 150 comprises processing andtransmit/receive circuitry for sending information from and receivinginformation at the UE device 104 a. Although one communication subsystem150 is illustrated, it could instead be multiple communicationsubsystems.

The communication subsystem 150 includes D2D communication circuitry 162for performing D2D communications between the master UE device 104 a andone, some, or all of the UE devices 104 b-d. This circuitry 162 cancomprise dedicated processing and transmit/receive circuitry, althoughit will be appreciated that more generally dedicated circuitry may notbe required.

In FIG. 2 one antenna 152 transmits wireless communication signals to,and receives wireless communications signals from, the RRH 108 a, andanother separate antenna 154 transmits D2D communication signals to, andreceives D2D communication signals from, the UE devices 104 b-d.However, more generally, it will be appreciated that one or moreantennas may be used for transmitting/receiving D2D communicationsignals, and these one or more antennas may be different from or thesame as one or more antennas used for transmitting/receiving thewireless communications to/from the RRH 108 a.

The D2D communications between the UE devices 104 a-d may be over Wi-Fi,and the antenna 154 may be or include a Wi-Fi antenna. As anotherexample, the D2D communications may be over Bluetooth™, and the antenna154 may be or include a Bluetooth™ antenna. As another example, the D2Dcommunications may utilize uplink and/or downlink resources (e.g. timeslots and/or frequencies) that may be scheduled by the radio accessnetwork 106. In general, the D2D communications may be over cellularspectrum (i.e., inband) or unlicensed spectrum (i.e., outband).

The D2D coordinator 160 coordinates the D2D communications amongst theUE devices 104 a-d. The D2D coordinator 160 may be functionalityimplemented in one or more of hardware, firmware, or software incombination with a processor to run the software. In the specificembodiment in FIG. 2, the D2D coordinator 160 is implemented by theprocessor 156 when the processor 156 accesses and executes a series ofinstructions stored in the memory 158, the instructions defining theactions of the D2D coordinator 160. When the instructions are executed,it causes the UE device 104 a to coordinate D2D communications betweenthe UE devices 104 a-d in the manner explained below. In otherembodiments, the D2D coordinator 160 may instead (or additionally)comprise dedicated integrated circuitry, such as an application specificintegrated circuit (ASIC), or a programmed field programmable gate array(FPGA) for performing one or more of the functions of the D2Dcoordinator 160. Therefore, more generally, the D2D coordinator 160 is amodule or unit that is part of the UE device 104 a and that isconfigured to implement the operations described below.

The D2D participator 161 receives instructions from the D2D coordinator160 to participate in D2D communications with one or more of the otherUE devices 104 b-d in the manner explained below. Similarly, althoughthe D2D participator 161 is illustrated as being defined by instructionsstored in the memory 158, which are to be executed by the processor 156to implement the D2D participator 161, this does not necessarily have tobe case (e.g. the D2D participator 161 could instead be dedicatedcircuitry). Therefore, more generally, the D2D participator 161 is alsoa module or unit that is part of the UE device 104 a and that isconfigured to implement the operations described below.

As shown in FIG. 2, the UE device 104 b similarly includes acommunication subsystem 164, two antennas 166 and 168, a processor 170,and a memory 172. The UE device 104 b also includes a D2D participator174.

The UE devices 104 c and 104 d include the same components describedabove with respect to the UE device 104 b. That is, UE device 104 cincludes communication subsystem 176, antennas 178 and 180, processor182, memory 184, D2D participator 186, and D2D communication circuitry188; and UE device 104 d includes communication subsystem 190, antennas192 and 194, processor 196, memory 198, D2D participator 200, and D2Dcommunication circuitry 202.

The D2D coordinator 160 may be considered a master in that the D2Dparticipators 161, 174, 186, and 200 take instructions from the D2Dcoordinator 160 and cause the D2D communications in the mannerinstructed by the D2D coordinator 160. In this sense, the D2Dparticipators 161, 174, 186, and 200 may be considered slaves.

FIG. 2 represents a snap-shot in time in which UE device 104 a is themaster UE device, and so is the only UE device that is illustrated ashaving a D2D coordinator. However, one or more other of the UE devices104 b-d could also have D2D coordinator functionality, which may beactivated if they were instead to become a master UE device. To theextent any of UE devices 104 b-d have D2D coordinators also, this hasnot been illustrated. Also, in some embodiments, it could be that someof UE devices 104 a-d are manufactured with D2D coordinatorfunctionality (which means that the UE device could become a master UEdevice if such functionality is activated), whereas other of the UEdevices 104 a-d (which may not be as sophisticated) could bemanufactured to not have D2D coordinator functionality and may only everbe slaves.

Example of a Master UE Device Coordinating D2D Communications to Assistwith Wireless Communication Between a Network and UE Devices:

In one embodiment, the D2D coordinator 160 is configured to determinewhich of the plurality of UE devices 104 a-d is/are to be assisted,using D2D communications, with wireless communications with the RRH 108a. Specifically, the D2D coordinator 160 in this embodiment isconfigured to perform the following operations, which are described withreference to FIG. 3.

In step 302, the D2D coordinator 160 determines that one of the UEdevices 104 a-d, which will be referred to as a “target UE device”, isto have assistance with wireless communication between the target UEdevice and the RRH 108 a, where the assistance uses D2D communications.Such assistance may include assistance in transmitting information fromthe target UE device to the RRH 108 a and/or assistance in receivinginformation from the RRH 108 a at the target UE device.

One example way in which the D2D coordinator 160 determines that atarget UE device is to have assistance is as follows: the D2Dcoordinator 160 obtains an indication that the target UE device hasrequested assistance, and by way of receipt of this indication, the D2Dcoordinator 160 determines that the target UE is to be assisted. Forexample, the target UE device may communicate directly with the masterUE device 104 a using D2D communications to inform the master UE device104 a that it requires or would like assistance.

In some embodiments, the D2D coordinator 160 determines that the targetUE device is to have assistance upon receiving a message from thenetwork 106 in which the network 106 informs the D2D coordinator 160that the target UE device has requested assistance or is to be assisted.For example, the centralized processing system 110 of the network 106may make this determination and cause a message to be sent from the RRH108 a to the master UE 104 a, which receives the message and forwardsthis to its D2D coordinator 160.

If the network 106 informs the D2D coordinator 160 that the target UEdevice requires assistance, then the network 106 must first make thisdetermination. The following are example ways in which this may occur.

(a) The network 106 may receive a message from the target UE deviceindicating that the target UE device needs or would like assistance.

(b) The network 106 may obtain an indication of a wireless channelquality between the target UE device and the RRH 108 a, and based onthis indication (e.g. the wireless channel quality being below aparticular threshold), the network 106 may determine that the target UEdevice requires assistance. An indication of wireless channel quality,as used herein, may be one or more channel quality indicator (CQI) orchannel state information (CSI) values, or the indication may be basedon a received sounding signal, e.g., sent by the target UE device. Asanother example, the indication of wireless channel quality may be anerror rate of information wirelessly communicated (e.g. between thetarget UE and the RRH 108 a). Examples of error rate include packeterror rate, bit error rate, and frame error rate.

(c) The network 106 may obtain a buffer status indicating how manypackets are to be transmitted from or received by the target UE, andbased on this buffer status (e.g. a buffer status showing a queue ofpackets above a certain threshold), the network 106 may determine thatthe target UE device requires and/or is to have assistance.

The network 106 may perform a combination of some or all of (a) to (c)above.

In another embodiment, the D2D coordinator 160 determines that thetarget UE device is to have assistance without receiving an explicitindication from the network 106 or the target UE device in this regard.Example ways in which the D2D coordinator 160 can do this are asfollows.

(i) The D2D coordinator 160 may determine that the target UE device isto have assistance based on an indication that the wireless channelquality between the target UE device and the RRH 108 a is low (below apredetermined threshold). The indication of wireless channel quality maybe received from the target UE device via D2D communication, or from thenetwork 106. Alternatively, if the target UE device is the master UEdevice 104 a (i.e. it is the master UE 104 a device that is to haveassistance), then the D2D coordinator 160 may obtain the wirelesschannel quality indication directly from the master UE 104 a deviceitself (e.g. via another module in the master UE 104 a device).

(ii) The D2D coordinator 160 may determine that the target UE device isto have assistance based on a buffer status message or value indicativeof how many packets are to be transmitted from or received by the targetUE device. The buffer status information may be received from the targetUE device (via D2D communication), from the network 106, or directlyfrom the master UE device 104 a itself.

A combination of (i) and (ii) above may be performed.

In some embodiments above, the target UE device determines that itrequires or would like assistance with wireless communication betweenthe target UE device and the RRH 108 a, and ultimately the master UEdevice is informed of this. Example ways in which the target UE devicecan make the determination are as follows.

(1) A user of the target UE device may manually instruct the target UEdevice to request assistance, e.g. by the user instructing the target UEdevice through a user interface.

(2) The target UE device may receive a message from the network 106 ordirectly from another UE device indicating that the target UE device isto request assistance.

(3) The target UE device may determine that it requires assistance basedon the quality of the wireless channel between the target UE device andthe RRH 108 a being below a particular threshold.

(4) The target UE device may determine that it requires assistance basedon a buffer status showing a queue of packets above a certain threshold.

The target UE device could perform a combination of some or all of (1)to (4) above.

Various ways in which the D2D coordinator 160 determines that the targetUE device is to have assistance are described above. As a simple exampleconsistent with one of the ways described above, the UE device 104 c maydetermine that it requires assistance due to a poor channel qualitybetween the UE device 104 c and the RRH 108 a. The UE device 104 c maythen directly communicate with the master UE device 104 a over a D2Dcommunication link to inform the D2D coordinator 160 of the master UEdevice 104 a. The D2D coordinator 160 may then determine that, becausethe UE device 104 c has requested assistance, the UE device 104 c is atarget UE device that is to have assistance.

With reference again to FIG. 3, in step 304, the D2D coordinator 160determines whether another UE device of the plurality of UE devices 104a-d, which will be referred to as the “helper UE device”, is to assistthe target UE with the wireless communication between the target UEdevice and the RRH 108 a. The following are example ways in which theD2D coordinator 160 can make this determination.

(a) The D2D coordinator 160 may receive a message indicative of whichone of the plurality of UE devices 104 a-d has the highest quality D2Dcommunication link with the target UE device, and the D2D coordinator160 may then select as the helper UE device the one indicated as havingthe highest quality D2D link. This helper UE device is determined to bethe UE device to assist the target UE device. The message indicative ofwhich of the plurality of UE devices 104 a-d has the highest quality D2Dcommunication link could be received from the target UE device via a D2Dcommunication. In such a case, the master UE device 104 a could directlycommunicate with the target UE device via D2D communications to requestsuch information. As another example, the message indicative of which ofthe plurality of UE devices 104 a-d has the highest quality D2Dcommunication link could be received from the network 106. Thissituation may occur if the target UE device previously provided suchinformation to the network 106. As another example, if the master UEdevice 104 a is the target UE device, then the D2D coordinator 160 couldobtain the information directly from the master UE 104 a device itself.In an alternative embodiment, rather than the message being indicativeof which one of the plurality of UE devices 104 a-d has the highestquality D2D communication link with the target UE device, the messagemay instead be indicative of which one(s) of the plurality of UE devices104 a-d has/have an acceptably high channel quality of D2D communicationlink with the target UE device (e.g. the quality being higher than apredetermined threshold), in which case the D2D coordinator 160 mayselect as the helper UE device one of UE devices 104 a-d indicated ashaving a D2D communication link of acceptably high quality.

(b) Assuming the helper UE device is different from the master UE device104 a, the D2D coordinator 160 may communicate directly with the helperUE device using D2D communication in order to enquire whether the helperUE device is able to assist the target UE device. The helper UE devicecan respond by providing an indication in this regard. The indicationmay be simply a “yes” or “no”, or other information that allows the D2Dcoordinator 160 to determine whether the helper UE device is to assistthe target UE device. Examples of such other information include thequality of the wireless channel between the helper UE device and thenetwork, and/or the quality of the D2D communication link between thehelper UE device and the target UE device, and/or the battery power ofthe helper UE device, and/or the processing capabilities of the helperUE device, and/or whether the helper UE device is connected to anexternal power source, and/or whether the helper UE device can provide aminimum level of security for handling packets of other devices. In someembodiments, the helper UE device may ask permission from its user (e.g.via a user interface), and only indicate that it can assist the targetUE device if the user provides permission.

(c) The D2D coordinator 160 may determine that the helper UE device isto assist the target UE device based on a wireless channel qualitybetween the helper UE device and the RRH 108 a being above apredetermined threshold determined by the D2D coordinator 160. Theindication of wireless channel quality may be received from the helperUE device via D2D communication, or from the network 106, or directlyfrom the master UE device 104 a itself (e.g. if the helper UE device isthe master UE device).

(d) The D2D coordinator 160 may determine that the helper UE device isto assist the target UE device based on a power availability of thehelper UE device being above a minimum threshold determined by the D2Dcoordinator 160. The indication of power availability may be receivedfrom the helper UE device, the network 106, or directly from the masterUE device 104 a. Power availability can include the amount of batterypower the helper UE device has and/or whether the helper UE device isconnected to an external power source.

(e) The D2D coordinator 160 may determine that the helper UE device isto assist the target UE device based on one or more specificcapabilities of the helper UE device, such as: a level of processingpower available to the helper UE device, and/or a level of storagecapacity available to the helper UE device, and/or a level of securitypossessed by the helper UE device for handling packets of other UEdevices (e.g. a helper UE device may, in some embodiments, need to becertified by the network to perform certain tasks requiring privacy andsecurity protection), and/or whether the helper UE device has apredetermined minimum level of baseband and/or RF communicationabilities, etc. In some embodiments, the helper UE device may berequired to possess a minimum level of wireless communication capability(e.g. particular RF front end capabilities, such as a minimum numberand/or quality of antennas, a minimum number and/or quality of low-noiseamplifiers, a minimum quality of the RF communication circuitry and/orfiltering, etc.). The D2D coordinator 160 may determine that the helperUE device is to assist based on or more of these specific capabilitiesbeing present and/or being above a minimum threshold determined by theD2D device coordinator 160. As above, the indication may be receivedfrom the helper UE device, the network 106, or directly from the masterUE device 104 a.

(f) The D2D coordinator 160 may receive from the network 106 a messageidentifying the helper UE device. The network 106 may determine thehelper UE device using any, some, or all of the factors discussed in (a)to (e) in the five paragraphs above.

The D2D coordinator 160 could perform a combination of some or all of(a) to (f) described in the six paragraphs above.

With reference again to FIG. 3, in step 306, where the D2D coordinator160 determines that the helper UE device is to assist the target UEdevice, then the D2D coordinator 160 instructs the helper UE device touse D2D communications to directly communicate with the target UE deviceto assist the target UE device with the wireless communication betweenthe target UE device and the RRH 108 a.

Assuming the helper UE device is different from the master UE device 104a, the D2D coordinator 160 may have the master UE device 104 a directlycommunicate with the helper UE device using D2D communications toinstruct the helper UE device. Alternatively, the master UE device 104 amay communicate with the network 106 to inform the network 106 that thehelper UE device is to assist, and the network 106 can then instruct thehelper UE device (or relay the message from the master UE device 104 a).In any case, it is the D2D participator in the helper UE device thatreceives the instructions and causes the helper UE device to assist thetarget UE device. If the master UE device 104 a is the helper UE device,then the D2D coordinator 160 may directly instruct the D2D participator161 of the master UE device 104 a.

The D2D coordinator 160 also instructs the target UE device to use theD2D communications to directly communicate with the helper UE device tobe assisted with wireless communication between the target UE device andthe RRH 108 a. This instruction may be transmitted to the target UEdevice directly, through the network, or relayed through the helper UEdevice.

Examples of Establishing and Re-Evaluating Target/Helper UE DeviceConfigurations:

In some embodiments, the D2D coordinator 160 may set up several targetUE device/helper UE device combinations/configurations, some examples ofwhich are shown in FIG. 4. Although multiple different configurationsare shown in sequence (A to F) in FIG. 4, it is contemplated that a D2Dgroup may assume only one or more of these configurations in anysequence and for different durations, or may assume other configurationsnot shown.

During time period A, the D2D coordinator 160 has determined that UEdevices 104 b and 104 c are target UE devices, that master UE device 104a is to be a helper UE device that will assist target UE device 104 b,and that UE device 104 d is to be a helper UE device that will assisttarget UE device 104 c.

The D2D coordinator 160 may select this specific target/helperconfiguration using any of the methods described above. As an example,the D2D coordinator 160 may receive information (received at the masterUE 104 a) indicating that the wireless channel quality between UE device104 b and the RRH 108 a is low (e.g. below a predetermined threshold),and indicating that the wireless channel quality between UE device 104 cand the RRH 108 a is also low, such that the UE devices 104 b and 104 care determined to be target UE devices that are to be assisted. The D2Dcoordinator 160 may receive further information indicating that the UEdevice 104 d has a wireless channel quality between the UE device 104 dand the RRH 108 a that is high (e.g. above a predetermined threshold),and that the UE device 104 c has a D2D communication link with the UEdevice 104 d of acceptably high quality (above a predeterminedthreshold), such that the UE device 104 d is determined to be a helperUE that is to assist target UE device 104 c. Similarly, the D2Dcoordinator 160 may receive further information indicating that themaster UE device 104 a has a wireless channel quality between the masterUE device 104 a and the RRH 108 a that is also high, and that the UEdevice 104 b has a D2D communication link with the master UE device 104a of acceptably high quality, such that the master UE device 104 a isdetermined to be a helper UE that is to assist target UE device 104 b.

After a period of time has elapsed, the D2D coordinator 160 mayre-evaluate to determine if any target/helper configurations are to bemodified. The period of time may be 1-2 seconds, although it could beshorter (e.g. 50 ms), or longer (e.g. more than 5 seconds). In someembodiments, the period of time may be under the control of the D2Dcoordinator 160 or under the control of the network 106. In someembodiments, the lapsing of the period of time could be determined basedon a change in factors such as channel conditions, UE device locations,etc., and may be determined by the network and/or the master UE device104 a. The re-evaluation could also occur dynamically based on factorssuch as a change in channel quality (between particular UE devices andthe base station and/or of certain D2D communication links) and/or achange in buffer status of one or more of the UE devices 104 a-d.

During the re-evaluation, the D2D coordinator 160 determines whether thehelper/target UE device configurations need to be modified. This may bebased on updated information relating to the determination of whichdevices require assistance and which devices are in the best position toprovide that assistance. The factors discussed earlier with respect tosteps 302 and 304 in FIG. 3 can be used for determining whether a UEdevice is to be (or remain) a target UE device and whether a UE deviceis to be (or remain) a helper UE device.

As an example, at the end of time period A, the D2D coordinator 160 maydetermine that UE devices 104 b and 104 c still require assistance withtheir wireless communications with the RRH 108 a, but that UE device 104d is now to assist UE device 104 b using D2D communications 318, andthat UE device 104 a is now to assist UE device 104 c using D2Dcommunications 316. This reconfiguration may be based on updatedinformation indicating that the UE device 104 d now has a better D2Dconnection with UE device 104 b (i.e. a D2D communication link of higherchannel quality), and that the UE device 104 a now has a better D2Dconnection with the UE device 104 c. The D2D coordinator 160 thereforehas master UE device 104 a communicate this reconfiguration informationto the UE devices, either directly using D2D communication or throughthe network 106. The result is that shown in time period B.

At the end of each time period in FIG. 4, the master UE device 104 are-evaluates to determine whether the helper/target UE deviceconfigurations may be modified or terminated. Various other examplehelper/target UE device configurations are illustrated in FIG. 4. Intime period C, the master UE device 104 a is a helper UE device andassists with the wireless communications between the RRH 108 a and eachof the target UE devices 104 b, 104 c, and 104 d. For example, if theD2D coordinator 160 determined that that master UE device 104 a had agood network connection to the RRH 108 a, as well as a good D2Dconnection to UE devices 104 b, 104 c, and 104 d, and the D2Dcoordinator 160 determined that the UE devices 104 b, 104 c, and 104 ddid not have a good (or as good of) a connection to the RRH 108 a, thenthe helper/target UE device configuration shown in time period C may beappropriate.

During time period D, upon re-evaluation the D2D coordinator 160determines that only master UE device 104 a requires assistance and thatUE device 104 d is an appropriate helper, and so D2D coordinator 160informs the UE devices of this and the only D2D communication is betweenUE device 104 d and UE device 104 a. During time period E, uponre-evaluation the D2D coordinator 160 determines that only UE device 104b requires assistance and that UE device 104 c and UE device 104 d areboth appropriate helpers, and so D2D coordinator 160 informs the UEdevices of this and the only D2D communications are between UE device104 b and UE device 104 c, as well as between UE device 104 b and UEdevice 104 d. During time period F, upon re-evaluation the D2Dcoordinator 160 determines that none of the UE devices 104 a-d requiresassistance with wirelessly communicating with the RRH 108 a, and so theD2D coordinator 160 informs the UE devices of this and no D2Dcommunications are utilized.

By having a master UE device 104 a determine target UE devices andcorresponding helper UE devices and possibly re-evaluating thetarget/helper UE device configurations over time, there may beassurances that the UE devices in a D2D group are provided with, andbenefit from, assistance with their wireless communications with thebase stations, as needed, through D2D communications. This may bebeneficial compared to ad hoc D2D communications between UE devices 104a-d without any D2D coordination, in which certain of UE devices 104 a-dmay not be able to secure assistance from the other members in the D2Dgroup (or may secure assistance from another D2D member who is not in agood position to assist them).

In the embodiments described above, re-evaluation of the target/helperUE device configurations is performed periodically after a particularperiod of time has elapsed, or on a dynamic basis. However, it mayinstead be the case that certain helper/target UE configurations arestatic (i.e. set up and then not changed for an extended period oftime). Also, it may be the case that the master UE device determineswhich UE devices are to assist each other, but lets the UE devicesthemselves decide who will be the helper(s) and target(s). In some ofsuch embodiments, the UE devices may change which one is the helper andwhich one is the target on their own accord or at the instruction of themaster UE device. In some embodiments, the target and helper UE devices,once chosen by the master UE device, may themselves have tocontrol/coordinate use of the wireless channel for their D2Dcommunications.

In the embodiments described above, a helper UE device is alwaysassisting with wireless communication between the target UE device andbase station. This needs not necessarily be the case. A helper UE devicemay instead (or also) assist with a D2D communication between the targetUE device and another UE device. More generally, a helper UE device maysimply be a UE device that sends information to or receives informationfrom a target UE device using a D2D communication link (e.g. datasharing). In such embodiments, the master UE device may still determinethe helper/target UE device configurations.

Examples of a Master UE Device Controlling Wireless Channel Access forD2D Communications:

In some embodiments, a D2D communication between first and second UEdevices may be coordinated by controlling use of the wireless channel inorder to mitigate interference with a D2D communication of at least oneother UE device during the D2D communication between the first andsecond UE devices.

FIG. 5 shows an example of controlling use of the wireless channel forthis purpose. FIG. 5 assumes that UE device 104 a is a helper UE devicethat communicates with target UE device 104 b using D2D communications312, and UE device 104 d is a helper UE device that communicates withtarget UE device 104 c using D2D communications 314. However, to try toprevent or eliminate the D2D communications 312 from interfering withthe D2D communications 314, the D2D coordinator 160 instructs the UEdevices 104 a-d to adhere to a time-division multiple access (TDMA)protocol in which the D2D coordinator 160 instructs the UE devices thatduring a first time slot D2D communications 312 may occur between UEdevices 104 a and 104 b, but not between UE devices 104 c and 104 d (asshown at time slot 1 in FIG. 5), and during a second time slot D2Dcommunications 314 may occur between UE devices 104 c and 104 d, but notbetween UE devices 104 a and 104 b (as shown at time slot 2 in FIG. 5).The time slots during which only D2D communications 312 are allowed, andthe timeslots during which only D2D communications 314 are allowed canalternate, as shown in FIG. 5. It is the D2D participators (i.e.participators 161, 174, 186, and 200) of each of the UE devices 104 a-dthat receive the D2D wireless channel access instructions from the D2Dcoordinator 160 and ensure that their UE device adheres to the D2Dchannel access protocol as instructed by the D2D coordinator 160. TheD2D coordinator 160 may instruct the UE devices 104 a-d by sending oneor more messages to the UE devices via D2D communication or via thenetwork 106 (i.e. the network 106 sends or forwards the instruction tothe UE devices).

TDMA is only one example of a channel access scheme/protocol that may beimposed by the D2D coordinator 160. Alternatively, the D2D coordinator160 may impose a frequency-division multiple access (FDMA) channelaccess scheme in which each D2D communication link is assigned one orseveral frequency bands, or channels, that are sufficiently differentfrom each other to try to mitigate interference. For example, one ormore frequency channels may be assigned to UE devices 104 a and 104 bfor their D2D communications 312, and a different one or more frequencychannels may be assigned to UE devices 104 c and 104 d for their D2Dcommunications 314. Alternatively, the D2D coordinator 160 may impose acode division multiple access (CDMA) channel access scheme in whichdifferent ones of the UE devices 104 a-d use different CDMA codes tomodulate their D2D communication signals. Alternatively, the D2Dcoordinator 160 may impose a space-division multiple access (SDMA)channel access scheme in which one or more of the UE devices 104 a-d areassigned or use different radiation patterns for D2D communications. Insome embodiments, there may be dedicated uplink or downlink resourcesassigned by the network 106 for D2D communications, and the D2Dcoordinator 160 may assign the UE devices 104 a-d different one(s) ofthe dedicated resources for the D2D communications to try to mitigateinterference between different D2D communications.

It will be appreciated that a combination of one or more of the exampleD2D channel access methods described in the paragraph above, and/orother D2D channel access methods, may be employed by the D2D coordinator160. By having the D2D coordinator 160 coordinate/control wirelesschannel access, the sharing of the resource (channel access) may besimplified compared to an ad hoc method in which the UE devices 104 a-dhave to negotiate channel access.

Example Ways in which Helper UE Device(s) May Assist with WirelessCommunication Between a Network and Target UE Device(s):

As a first example, a helper UE device may decode and forwardinformation to one or more target UE devices. For example, if a targetUE device fails to correctly decode a packet received directly from thebase station over a wireless channel because of noise or interference inthe wireless channel between the target UE device and the base station,then the helper UE device may receive and decode the packet, and thenforward the decoded packet (or its information) to the target UE devicevia a D2D communication link. The opposite operation may occur on theuplink. That is, a target UE device may forward packets destined for thebase station to the helper UE device via the D2D communication linkbetween the target UE device and the helper UE device, and then thehelper UE device may transmit such packets (or information in thepackets) to the base station over the wireless communication linkbetween the base station and the helper UE device.

FIG. 6 shows an example of a “decode-and-forward” operation. FIG. 6assumes the UE device 104 a is the helper UE device, and UE devices 104b, 104 c, and 104 d are target UE devices. Control signals are sent fromthe RRH 108 a directly to each of the UE devices 104 a-d, but signalscarrying data are sent from the RRH 108 a only to the helper UE device104 a, and the helper UE device 104 a decodes and forwards the data toeach of the other UE devices 104 b-d through D2D communication.Specifically, control signals 362 for the UE device 104 b aretransmitted from the RRH 108 a to the UE device 104 b directly over thewireless channel between the RRH 108 a and the UE device 104 b, as arecontrol signals 364 for the UE device 104 a, control signals 366 for theUE device 104 c, and control signals 368 for the UE device 104 d. Thecontrol signals may be broadcast signals or multicast signals or unicastsignals specific to each UE device. With regard to the data packets, theRRH 108 a wirelessly transmits to helper UE device 104 a data packets370, which are ultimately destined for UE device 104 d, as well as datapackets 372, which are ultimately destined for UE device 104 c, and datapackets 374, which are ultimately destined for UE device 104 b. Thehelper UE device 104 a then: (i) decodes and forwards data packets 370to target UE device 104 d over D2D communication link 376, (ii) decodesand forwards data packets 372 to target UE device 104 c over D2Dcommunication link 378, and (iii) decodes and forwards data packets 374to target UE device 104 b over D2D communication link 380. In FIG. 6,just the data packets are illustrated as being decoded and forwarded. Itcould instead be the case that some or all of the control signals arealso or instead decoded and forwarded in a manner similar to the datapackets 370, 372, and 374.

As another example, a helper UE device may collect all or some of uplinksignaling from one or more target UE devices and forward such signalingto the network. FIG. 7 shows an example of aggregating uplink signalingin accordance with one embodiment. Uplink control signals 386 of targetUE device 104 b that are destined for RRH 108 a are transmitted directlyfrom target UE device 104 b to helper UE device 104 a over D2Dcommunication link 388. Similarly, uplink control signals 390 of targetUE device 104 c that are destined for RRH 108 a are transmitted directlyfrom target UE device 104 c to helper UE device 104 a over D2Dcommunication link 392. Similarly, uplink control signals 394 of targetUE device 104 d that are destined for RRH 108 a are transmitted directlyfrom target UE device 104 d to helper UE device 104 a over D2Dcommunication link 396. The helper UE device 104 a then aggregates suchsignals and directly wirelessly transmits them to RRH 108 a. Examples ofuplink signaling that may be aggregated in the manner shown in FIG. 7include: acknowledgement (ACK) signals, and/or CQI signals, and/orrandom access channel (RACH) signals, and/or “keep-alive” signals.

Although the aggregation described in relation to FIG. 7 is with respectto uplink control signals, the aggregation may be performed on thedownlink as well (or instead) for some downlink control signals. Thatis, control signals destined for some or all of the plurality of UEdevices 104 a-d may just be sent from the RRH 108 a to helper UE device104 a, which then distributes them to the other UE devices 104 b-d usingD2D communication.

The aggregation described above may be particularly beneficial when theuplink signals from the target UE devices are not delay sensitive, asthere may then not be as much of a concern with the delay associatedwith the helper UE device collecting such uplink signals through the D2Dcommunications and aggregating them into one or several transmissions tothe RRH 108 a.

Another possible benefit of the aggregation is that it may free up someuplink resources (and therefore also possibly improve spectralefficiency) between the RRH 108 a and the UE devices 104 a-d. Forexample, if the D2D communications are out-of-band and do not utilizethe RRH 108 a uplink resources, and if several of such uplink signalscan be aggregated and transmitted by the helper UE device 104 a on theuplink using fewer resources, then this may save uplink resourcescompared to each target UE device using its own uplink resources totransmit its uplink control signals directly to the RRH 108 a. This mayresult in a reduction in overhead associated with the signaling sinceeach UE device 104 a-d is not using uplink resources to transmit itscontrol signals to the RRH 108 a.

Another possible benefit of the aggregation is that it may lower thenumber of feedback signals sent to the RRH 108 a. For example, thehelper UE device may be able to send a single feedback signal thatreports the feedback of multiple target UE devices. As an example, thehelper UE device may be able to send a single CQ1 value and/or singleCSI value for the collective channel. Specifically, one or more of theUE devices 104 a-d may determine a CQI or CSI value defined based on theplurality of channels (between each device 104 a-d and the RRH 108 a)and their qualities when the devices 104 a-d are helping each other.This may be referred to as the collective CQI, and it may be morestable, such that it may need to be updated less frequently. Also, sinceit is one feedback value for the whole D2D group, it may reduce theoverhead per device. Therefore, in general, the feedback efficiency mayincrease as the number of target UE devices increase. In particular,there may be fewer feedback signals per UE device, or the feedbackoverhead may not grow (or not grow as fast) with the D2D group sizecompared to if each UE device were sending its own feedback signalsdirectly to the access network. The master UE device may determine whichone(s) of the UE devices is/are to compute the collective CQI and sendit to the network, or the master UE device may itself compute thecollective CQI and send it to the network.

With regard to the collective channel discussed above, a helper UEdevice that is stationary or that is nomadic, but does not move toooften, may have a relatively stable channel due to lack of movement, andthis may stabilize the collective channel, for example, if decode andforward operations are being performed in which information transmittedto/from the network and the members of the D2D group goes through thewireless communication link between the helper UE device and the basestation.

As another example, a helper UE device may act as a proxy, receivingcontent directly from the base station and forwarding the content, viaD2D communications, to any target UE devices that request the contentand/or that are interested or are meant to receive the content. FIG. 8shows an example of a UE device acting as a proxy for other UE devices.Content 402 is wirelessly transmitted from the RRH 108 a to the helperUE device 104 a via the wireless channel between the helper UE device104 a and the RRH 108 a. The helper UE device 104 a then queries to seewhich of the target UE devices 104 b-d are interested in (or are toreceive) the content 402, and directly transmits, using D2Dcommunications, the content 402 to the appropriate target UE devices 104b-d. In FIG. 8 it is assumed that each one of target UE devices 104 b-dare to receive the content 402, and so helper UE device 104 a: (i)transmits the content 402 directly to target UE device 104 b via D2Dlink 404, (ii) transmits the content 402 directly to target UE device104 c via D2D link 406, and (iii) transmits the content 402 directly totarget UE device 104 d via D2D link 408. The configuration in FIG. 8 isan example of how the master UE device can have a helper UE deviceassist in delivery of high demand content.

With respect to FIGS. 6 to 8, in some embodiments, the master UE devicemay choose the helper and target UE devices using the criteria discussedherein. The master UE device may instruct the helper UE device and/ortarget UE device specifically to perform the decode and forward,aggregation or proxy operation, or the target and helper UE devices maydetermine this themselves through direct D2D communication.Alternatively, the network may indicate that the decode and forward,aggregation or proxy operation is to be performed. In some embodiments,the master UE device may correspond with the network and/or the UEdevices to set up the decode and forward, aggregation or proxy service.Also, although the master UE device 104 a is illustrated as being thehelper UE device in FIGS. 6 to 8, this needs not be the case. Anotherone of the UE devices 104 b-d could instead be the helper UE device ifit has suitable credentials.

In the examples described above with respect to FIGS. 6 to 8, thenetwork 106 may consider the D2D group of UE devices 104 a-d to be asingle virtual user equipment device (VUE) with the master UE device(MUE) acting as the master of the VUE. The MUE may also be called a “VUEmaster node”. The network 106 may associate the VUE with a singleidentification (ID) administered by the MUE or a helper UE device (e.g.if the MUE is not a helper UE device), and when certain information istransmitted between the RRH 108 a and members of the VUE, theinformation is only transmitted between the MUE (or helper UE device)and the RRH 108 a, and that information is distributed to/collected fromother VUE members via D2D communications.

The master UE device may also set up or establish the VUE. For example,the master UE device may acquire the VUE ID and announce it to themembers of the D2D group (e.g. using D2D communication), and/or themaster UE device may incorporate UE devices into the VUE. In embodimentsin which the network can assign some resources (e.g. time or frequency)to the VUE, the master UE device may acquire those resources from thenetwork. The master UE device may also set up a resource sharingmechanism between UE devices in the VUE (i.e. control use of thewireless channel for the D2D communications amongst the UE devices inthe VUE, as discussed above in relation to FIG. 5).

Another example way in which a helper UE device may assist one or moretarget UE devices is as follows. Both the helper UE device and a targetUE device may receive a signal transmitted from the RRH 108 a thatcarries one or more packets destined for the target UE device. Thehelper UE device may then transmit to the target UE device, via D2Dcommunications, the signal as received by the helper UE device. Thetarget UE device may then use this additional information to decode thepackets carried by the signal. Effectively, it may be as if the targetUE device and helper UE device were one device with multiple antennascomprising the antenna(s) of the target UE device and the antenna(s) ofthe helper UE device. This effective increase in receive antennas mayincrease the chances that the packets are decoded correctly. This formof assistance can be referred to as a linear technique.

Another example way in which a helper UE device may assist one or moretarget UE devices is as follows. The helper UE device may be able tocorrectly decode a source of interference that is affecting both thehelper UE device's wireless communications with the base station and thetarget UE device's wireless communications with the base station. Thehelper UE device can then forward information about the interferencedirectly to the target UE device via D2D communication, and the targetUE device may be able to partially or fully cancel the interferenceusing the information received from the helper UE device. This form ofassistance can be referred to as a non-linear technique.

In the linear and non-linear techniques described above, the master UEdevice may choose the helper and target UE devices. Also, the master UEdevice may instruct the helper UE device specifically to perform thisform of assistance (and the target UE device to be assisted in thisway), or the target and helper UE devices may determine this themselvesthrough direct D2D communication. In other embodiments, the network mayindicate that this form of assistance is to be performed.

Another example way in which a helper UE device may assist one or moretarget UE devices is as follows. Normally, if not being assisted, eachtarget UE device would need to wake up on a periodic basis to listen forpaging messages from the network. Instead, the helper UE device couldwake up more often or stay awake and listen for paging messages for thetarget UE devices it is assisting. Then, when a paging message destinedfor a target UE device is received, the helper UE device could wake upthe target UE device using D2D communication, and/or forward the pagingmessage using D2D communication. In this way, target UE devices may notneed to wake up to listen for paging messages, but instead may receivethem through D2D communication from the helper UE device. This mayresult in improved battery management. Also, in some embodiments, asingle paging message may be sent to the helper UE device that indicateswhich UE devices in the D2D group are being paged. This “group paging”message may be sent on a periodic basis, and the periodic basis may bemore frequent than other paging messages. The helper UE device can thenwake up and/or forward paging messages to the appropriate target UEdevice(s). In this way overhead may be reduced due to the sending of asingle paging message that pages multiple UE devices in the D2D group.Also, if the group paging message is sent more frequently than normal,this may result in a faster wakeup time for UE devices in the D2D groupsince there will be a shorter duration between when the networkdetermines that a UE device is to be paged and when the group pagingmessage (having the page in it) is sent. Also (or instead), the helperUE device, upon receiving the group paging message, may be able to wakeup multiple target UE devices at the same time via the D2Dcommunications, which may result in a faster wakeup time compared tosequentially paging and waking up each UE device being paged. It will beappreciated that the master UE device may choose the helper and targetUE devices that participate in the group paging scheme, and the masterUE device may correspond with the network and/or the UE devices to setup the group paging.

Another example way in which a helper UE device may assist one or moretarget UE devices is as follows. Normally, if a target UE device wantsto obtain the attention of the base station to obtain an uplink resourceassignment, it can use the RACH. This may involve delays, such aswaiting for the opportunity to send a message on the RACH and/orcolliding with other messages when transmitting on the RACH. However,with a helper UE device already awake and connected to the base station,rather than using RACH, the target UE device can transmit a messagedirectly to the helper UE device using D2D communications, and thehelper UE device can then communicate with the base station using itsestablished connection to secure an uplink resource for the target UEdevice. This may result in faster resource assignment in the uplink fora target UE device.

Also, or alternatively, the target UE devices may send their bufferstatuses to a helper UE device, rather than each target UE deviceindividually and independently using a RACH to request uplink resourcesto send the data in their buffer. Then, the helper UE device can send agroup buffer status update comprising the buffer status of each of thetarget devices. The helper UE device may send this on the RACH. Based onthe group buffer status update, the network can dedicate the appropriateuplink resources for each of the target UE devices. This may replace orreduce RACH delay and/or result in higher layer overhead reduction.

The master UE device may instruct the helper UE device and/or thenetwork to set up the group buffer status update. The master UE devicemay also choose the helper and target UE devices participating in thegroup buffer status update scheme and instruct them accordingly.

Another example way a helper UE device may assist one or more target UEdevices is by reducing power consumption and/or battery drainage of theone or more target UE devices by acting as a relay between the one ormore target UE devices and the base station so that, for at least somecommunications between a target UE device and the base station, thetarget UE device only has to transmit information to/receive informationfrom the helper UE device through D2D communications. The helper UEdevice takes care of the transmission/reception of the informationto/from the base station.

Another example way in which a helper UE device (and/or master UEdevice) may assist one or more target UE devices is by coordinatingnetwork coding amongst a plurality of UE devices in the D2D group.

A helper UE device may assist the network. For example, the network maybe able to send to the helper UE device information for a target UEdevice that the network is not able to send to the target UE devicedirectly because of a poor wireless channel. The helper UE device maythen forward such information to the target UE device through a D2Dcommunication link. As another example, the helper UE device assistingthe target UE devices with their wireless communications with the basestation may cause the collective channel of the D2D group to be morestable in time and/or frequency (i.e. vary more slowly), which mayresult in a physical layer signaling overhead reduction, for example, bynot needing to send updated CQI and/or CSI values as often. The grouppaging and group buffer status updates described earlier may also reducenetwork overhead. Thus, a master UE device may coordinate a helper UEdevice in a way to result increased network performance and/orefficiency.

The establishment of a master UE device may also help with the D2Ddiscovery process. For example, once a master UE device is established,the network may then send a message to other UE devices (e.g. throughunicast or multicast) in close physical proximity indicating that thereis a master UE device in the area. This may then cause the UE devices toinitiate a discovery process to discover the master UE device and/orjoin a D2D group. In some embodiments, this may be a simpler or fasterdiscovery protocol and/or may result in a smoother D2D group (or VUE)setup compared to having every D2D-enabled UE device periodicallysending out discovery messages and/or listening for discovery messagesin hopes that there may be a master UE device (or another D2D-enabled UEdevice or a D2D group) in close proximity. In some embodiments, themaster UE device may also assist with network registration. For example,the master UE device itself (or another helper UE device chosen by themaster UE device) may register the D2D group (or VUE) with the network.As another example, a UE device may have too weak of a networkconnection over the access channel to register with the network, but theUE device may be able to communication directly with the master UEdevice (or another helper UE device) using D2D communications, and themaster UE device (or the another helper UE device) may register the UEdevice with the network. More generally, the master UE device may takeresponsibility for the signaling and planning responsible for networkregistration (i.e. network registration of a D2D group, VUE, or aparticular UE device).

The establishment of a master UE device may also assist with two-tierhybrid automatic repeat request (HARQ) and/or acknowledgement(ACK)/negative-acknowledge (NACK), as follows. The HARQ and/or ACK/NACKsignaling may be two tiered in that the plurality of UE devices formingthe D2D group may first determine if any one of them is able tosuccessfully decode a message sent from the base station. If none are,then a single NACK may be sent to the base station. Otherwise, if one ormore UE devices are able to successfully decode the message, then anyNACK is resolved within the D2D group using D2D communications. Forexample, if a message from the network is meant for a target UE devicein the D2D group, and that target UE device is unable to successfullydecode the message, but a helper UE device is, then rather than thetarget UE device automatically sending a NACK to the base station, thetarget UE device first waits to see if a helper UE device has decodedthe message and can send it to the target UE device through D2Dcommunications. As another example, if the message from the base stationis meant for several target UE devices served by a helper UE device, aslong as one of them correctly decodes the message, it may then betransmitted to the others through D2D communication. The master UEdevice may assist in administering the two-tier process. For example,the master UE device may set up the two-tier process and/or determinethe target and helper UE devices. As another example, any target UEdevice that did not correctly receive a packet may send their NACK tothe master UE device, which may then determine whether the packet wascorrectly decoded by any other UE device in the D2D group and, if so,have the correctly decoded packet sent to the target UE device over aD2D communication link. If the master UE device cannot resolve the NACKwithin the D2D group, it may forward the NACK to the base station. Themaster UE device may control the timing of a two tier HARQ timer and/orset up or coordinate a higher tier acknowledgement signaling node in theD2D group to try to mitigate conflict in sending two-tier messages.

In view of the many examples above, more generally it will beappreciated that the assistance may be coordinated by havingcommunications between the base station and the target UE device relayedthrough the helper UE device, where the communication is transmittedbetween the target and helper using D2D communication, and thecommunication is transmitted between the helper and the base stationusing an access communication over an access channel. The master UEdevice can instruct the target and helper to set up this assistance. Asan example, the D2D coordinator may transmit an instruction to thetarget UE device to instruct the target UE device to send data to thehelper UE device (via D2D communication), to be relayed to the basestation, or the target UE device may be instructed to use the D2Dcommunication to receive data from the base station that has beenrelayed through the helper UE device. As another example, the D2Dcoordinator may instruct a helper UE device to receive a plurality ofinformation, the plurality of information including a portion ofinformation that either is received by the helper from a target UEdevice using D2D communication between the helper and target and is tobe transmitted by the helper to the network, or is received by thehelper from the network and is to be transmitted from the helper to thetarget using the D2D communication between the helper and target. Forexample, the “information” could be control signals being aggregated, asin FIG. 7, or a decode-and-forward of several packets, as in FIG. 6(e.g. the “plurality of information” could be packets 370, 372, and 374in FIG. 6, and the “portion of information” could be packet 370, whichis forwarded from helper 104 a to target 104 d). As another example, the“portion of information” could be a buffer status of one particular UEdevice, and the “plurality of information” could be the group bufferstatus update. As another example, the “plurality of information” couldbe a paging signal indicating which D2D devices being paged, and the“portion of information” could be the indication in the paging signalthat a particular UE device is being paged. It will also be appreciatedthat the network may be aware of the status of one, some or all of theUE devices in a D2D group (e.g. who is a helper, a target, a master UE),as well as which particular UE devices have a willingness to help thenetwork (e.g. receive a group paging signal so that paging overhead maybe reduced in the manner explained earlier). The network may use thisstatus information to work with a master UE device and/or helper UEdevice(s) to assist in wireless communication between the network andthe D2D group. For example, signalling and communication may beperformed through a helper UE device (e.g. as in the FIG. 7).

Example Ways in which a Master UE Device May be Selected andEstablished:

In one embodiment, the network 106 may select the master UE device 104a. This may occur in the central processing system 110 of the network106, although it could instead occur within the RRH 108 a itself,particularly if the plurality of UE devices 104 a-d are all connected tothe network 106 through the same RRH (which is the case in theillustrated embodiment). If a network selects the master UE device, itmay inform the selected UE device that it is a master UE device bysending such a message to the UE device from a base station of thenetwork.

The following are example ways in which the network 106 may determinethat a master UE device is to be established.

(a) The network 106 may receive a message from one or more of theplurality of UE devices 104 a-d (via RRH 108 a), the message requestingthat a master UE device be established. The message need not necessarilybe an explicit request from the UE device that a master UE device beestablished, although it could be. Alternatively, it may be some form of“complaint” or report from the UE device indicating poor D2Dcommunication performance (e.g. unacceptable or undesirable interferencebetween D2D communications or unacceptable or undesirable helper/targetconfigurations). Alternatively, a “message” per se may not be receivedby the network 106, but instead the network 106 may observe poorquality, inefficiency, and/or performance of one or more UE devices(e.g. an inefficiency of a direct communication between a UE device andthe network due to a low quality communication link, high error rate,etc.), and determine based on this that the one or more UE devices coulduse assistance from a neighbouring UE device through D2D communications.On this basis, the network may determine that a master UE device is tobe established so that the master UE device can coordinate and controlthis assistance.

(b) The network 106 may automatically determine that a master UE deviceis to be established when it is informed by one of the plurality of UEdevices 104 a-d that a D2D group has been established, or when thenetwork 106 establishes the D2D group. In some embodiments, the network106 may determine that a master UE device is to be established when theD2D group becomes bigger than a predetermined size (e.g. more than threeUE devices).

(c) The network 106 may determine that a master UE device is to beestablished upon receiving a request from a UE device that it be amaster UE device. For example, a user of the UE device may requestthrough a user interface of the UE device that the UE device become amaster, and the UE device may transmit this request to the network. Thenetwork 106 may automatically select as the master UE device the UEdevice that requests that it be a master UE device. Alternatively, eventhough the UE device may request that it be a master UE device, thenetwork 106 may only select this UE device as a master UE device if theUE device meets a predetermined minimum amount of the criteria discussedlater for selecting a master UE device.

(d) The network 106 may identify a candidate D2D group based onknowledge by the network 106 that a group of UE devices are in closephysical proximity to each other. For example, each of the UE devicesmay transmit their global positioning system (GPS) information to thenetwork 106, and the network 106 may compare such GPS information, andif the GPS information reveals that the UE devices are within apredetermined physical distance from each other (e.g. within 20 meters),then the network 106 may identify the UE devices as a candidate D2Dgroup. As another example, the network 106 may perform network-basedlocation by means of triangulation between base station towers todetermine the physical location of UE devices. Upon identifying acandidate D2D group, the network 106 may automatically determine that amaster UE device is to be established and select one of the UE devicesas the master UE device.

The network 106 may perform a combination of some or all of (a) to (d)in the four paragraphs above in order to determine that a master UEdevice is to be established.

In other embodiments, one or more of the UE devices themselves maydetermine that a master UE device is to be established. The network 106may instruct one or more of the UE devices to establish the master UEdevice. Alternatively, a UE device itself in a D2D group may decide thata master UE device needs to be established. This may be based on poorD2D communication performance. When the D2D group itself selects themaster UE device, this may be done through a negotiation process betweenthe UE devices in order to choose a master UE device amongst them thatbest (or acceptably) meets the master UE device selection criteriadiscussed later. One way the UE devices in the D2D group may communicatewith each other to establish a master UE device is through the network106, which may be beneficial if there is no way (or no efficient way) tocoordinate the use of wireless channel access for the D2D communications(since there is not yet a master UE device). Another way the UE devicesin the D2D group may communicate with each other to establish a masterUE device is through direct D2D communications, such as through usingcontention based communication. As an example, the D2D group maycommunicate with each other using virtual full duplex two dimensionalsparse code multiple access. An example of this is disclosed in the PCTpatent application publication WO2014090204.

If a master UE device is to be selected, whether it be by the network106, or by UE devices (e.g. UE devices 104 a-d in a D2D group), themaster UE device may be selected based on particular selection criteria,examples of which are listed below:

(a) It may be beneficial if the master UE device is stationary, or isnomadic but does not move too often or too fast. This is because a UEdevice that moves too often or too fast may soon leave the D2D group,causing there to no longer be a master UE device in the D2D group (andperhaps causing the selection process to begin all over again to selecta new master UE device). Therefore, how stationary a candidate master UEdevice is may factor into the criterion or criteria for selecting themaster UE device. For example, a candidate master UE device may not beselected if its physical location changes (or changes at an average ratemore than a predetermined amount) over a predetermined period of time.There are different ways to determine whether or how often (or fast) acandidate master UE device is moving. For example, the candidate masterUE device could have an accelerometer that provides data indicative ofmovement of the candidate master UE device. This data may be transmittedfrom the candidate master UE device to the entity evaluating theselection criteria (e.g. the network 106 or another UE device). Trackingthe location of the candidate master UE device (e.g. using GPS) overtime may also provide an indication of how often or fast the candidatemaster UE device is moving. How fast the wireless channel between thecandidate master UE device and the network is changing may also (orinstead) provide an indication of how often or fast the candidate masterUE device is moving.

(b) It may be desirable that a user of the candidate master UE deviceeither requests to be a master UE device or gives permission to be amaster UE device (e.g. through a manual prompt via a user interface).The selection criterion or criteria may therefore incorporate this as afactor.

(c) It may be beneficial if the master UE device has adequate poweravailability (e.g. available battery power above a predeterminedthreshold or connection to an external power source). The selectioncriteria or criterion may therefore incorporate this as a factor.

(d) It may be beneficial if the master UE device has a quality of acommunication link between the master UE device and the network that isabove a predetermined quality threshold. The selection criteria orcriterion may therefore include whether a candidate master UE device hassuch a network connection. For example, if this is not met, then acandidate master UE device may not be chosen as the master UE device.

(e) It may be beneficial if the channel properties of the communicationlink between the candidate master UE device and the network are notchanging, or are changing at a rate that is less than a predeterminedvalue over a given period of time. Therefore, the selection criteria orcriterion may incorporate this as a factor.

(f) It may be beneficial if the master UE device has a D2D communicationlink with other UE device(s) in the D2D group that is above a minimumthreshold of quality and/or that the master UE device has D2Dcommunication links with other UE device(s) in the D2D group that havechannel properties that do not change or change less than apredetermined amount over a predetermined period of time. Therefore, theselection criterion or criteria may factor this in (e.g. a candidatemaster UE device may not be selected as the master UE device if it has aD2D communication link with at least one other UE device in the D2Dgroup that is below a predetermined minimum level of quality).

(g) The selection criterion or criteria may factor in the physicallocation of a candidate master UE device relative to the physicallocation of other UE devices in the D2D group. For example, a candidatemaster UE device may not be chosen as the master UE device if it is at aphysical boundary location of the D2D group, as this may indicate thatthe candidate master UE device may soon be out of physical range or havepoor quality D2D communication links with other D2D group UE devices onthe other side of the physical space defining the D2D group. Thephysical location of the candidate master UE device may have to meet aminimum threshold of acceptability. In this way, the master UE devicemay be more strategically placed/located.

(h) Other selection criteria may include terminal capabilities of acandidate master UE device, such as whether the candidate master UEdevice has a predetermined level of security for handling packetsbelonging to others of the plurality of UE devices (e.g. a master UEdevice may need to be certified by the network to perform certain tasksrequiring privacy and security protection), and/or whether the candidatemaster UE device has at least a predetermined minimum level ofprocessing capabilities, and/or whether the candidate master UE devicehas at least a predetermined minimum level of storage capabilities,and/or whether the master UE device has at least a predetermined minimumlevel of wireless communication capabilities, such as baseband and/or RFfront end capabilities (e.g. the number and/or quality of antennas, thenumber and/or quality of low-noise amplifiers, the quality of the RFcommunication circuitry and/or filtering, etc.).

Selection criteria may include one, some, or all of the exampleselection factors in (a) to (h) in the eight paragraphs above. If thenetwork 106 is selecting the master UE device, then it may receiveinformation from candidate master UE devices indicative of the selectioncriteria, and decide which candidate master UE device is to be themaster UE device based on which of the candidate master UE devices bestmeets the selection criteria (or alternatively by choosing any one ofthe candidate master UE devices that acceptably fits within theselection criteria). Alternatively, if UE devices in a D2D group are tothemselves negotiate a master UE device, a volunteer UE device in theD2D group may receive and compare such information and select as themaster UE device the candidate master UE device that best meets (oracceptably fits) the selection criteria.

The selection criteria discussed above are examples of metrics used todetermine the master UE device. The metrics could be networkset/assigned or predefined. Selecting the master UE device may be basedon a metric optimization.

The master UE device may be permanently selected, or alternatively itmay be dynamically selected in that the selection may be re-evaluated(e.g. by the network or by one or more of the UE devices in the D2Dgroup) on a periodic basis to determine whether the master UE device isstill suitable. For example, if upon re-evaluation it is determined thatthe master UE device no longer has a good connection to the network,then it may have its master UE device status revoked. In suchembodiments, a new selection process may begin to select a new master UEdevice. Also, in some embodiments, a new master UE device may only beselected on an “as-needed” basis when a current master UE device leavesthe D2D group or loses its ability to adequately perform the functionsof a master UE device (e.g. the master UE device loses its connectionwith the access network and/or loses its D2D connection(s) with one ormore of the other UE devices in the D2D group and/or the master UE isleaving or has left the D2D group and/or a more capable, or potentiallymore capable, UE device has entered the D2D group). The master UE devicestatus could also be temporarily delegated to another UE device.

In some embodiments, when it is determined that a new master UE deviceis to be selected, then assuming the current master UE device still hasthe ability to act as a master UE device, the new master UE device isselected before the current master UE device has its master UE devicestatus revoked. This may allow for a seamless transition from one masterUE device to another.

Example Network Operations:

The role of the network varies in different embodiments. In someembodiments, the network is not involved in any aspect of establishingthe master UE device and D2D coordination. For example, one or more UEdevices in a D2D group may determine that a master UE device is to beestablished, and the master UE device may be selected by one of the UEdevices in the D2D group in the manner discussed above, and then thatmaster UE device may coordinate the D2D communications without thenetwork 106 knowing, or perhaps with the network 106 only being informedthat this is happening as a courtesy or to have the master UE devicenetwork-sanctioned. On the other hand, the network 106 may control muchof the process. For example, the network 106 may establish the D2D groupand determine that a master UE device is to be established, may selectthe master UE device, and may inform the master UE device of the levelof coordination that the master UE device is able to perform. Thenetwork may also select one or more helper and/or target UE devices. Themaster UE device may communicate to the network information such as thetarget/helper configurations and/or the performance or needs of the UEdevices in the D2D group (e.g. the buffer status of the UE devices, thechannel quality of the D2D communication links between the different D2Ddevices, etc.). Any involvement of the network between the two extremesof no network involvement and full network involvement is contemplated.

FIG. 9 shows an example of operations that may be performed by anetwork, e.g. network 106, in accordance with one embodiment.

In step 502, the network establishes a wireless connection andwirelessly communicates with at least one of a plurality of UE devicesthat are in physical proximity to each other, where at least two of theplurality of UE devices able to directly communicate with each otherusing D2D communication.

In step 504, the network sends to at least a master UE device of theplurality of UE devices an indication of one or more actions that are tobe performed by the master UE device to coordinate D2D communicationsamongst the plurality of UE devices. For example, the message sent fromthe network may indicate that the master UE device is to select targetUE devices and helper UE devices in the D2D group in the mannerexplained earlier. The message may indicate how often the master UEdevice is to re-evaluate the target/helper combinations. The message mayindicate that the master UE device is to control use of the wirelesschannel for D2D communications between UE devices and indicate whichtype of channel access method should be used (e.g. TDMA). In any case,it will be appreciated that the message does not have to literally tellthe master UE device which actions to perform. For example, it could bethat any UE device selected as a master UE device is configured toperform one or more predetermined actions (e.g. select target and helperUE devices and control wireless channel access for the D2Dcommunications). The message in such an embodiment may just be anindication that the master UE device is to now begin to perform suchpredetermined actions. In some of such embodiments, the message may bethe same message (or part of the same message) that the network sends tothe UE device to let the UE device know that the UE device has beenestablished as the master UE device.

In some embodiments, the method performed by the network may includesome or all of the following operations: determining that a master UEdevice is to be established and selecting one of a plurality of UEdevices as a candidate master UE device; sending a first message to thecandidate master UE device requesting that the candidate master UEdevice be the master UE device; receiving a response from the candidatemaster UE device indicating that the candidate master UE device iswilling to be the master UE device; receiving a message from the masterUE device indicating that D2D connections are established between themaster UE device and other of the plurality of UE devices for the masterUE device to coordinate the D2D communications amongst the plurality ofUE devices; sending to the plurality of UE devices a command to begintaking instructions from the master UE device; sending to at least themaster UE device an indication of one or more actions that are to beperformed by the master UE device to coordinate the D2D communications.

In some embodiments, the method performed by the network may includesome or all of the following operations: determining that a master UEdevice is to be established and sending a request to establish a masterUE device, the request being sent to at least one of a plurality of UEdevices; receiving from one or more of the plurality of UE devices anindication of one or more candidate master UE devices amongst theplurality of UE devices; for each of the one or more candidate master UEdevices, determining whether the candidate master UE device is permittedto be the master UE device, and if the candidate master UE device ispermitted to be the master UE device, then adding the candidate masterUE device to a list of survived master UE device candidates; sending arequest asking that the survived master UE device candidates negotiateto choose the master UE device, the request sent to at least one of theplurality of UE devices (the negotiating may include different survivedmaster UE devices requesting to be a master UE device and one of themdetermining who is to be the master UE device based on which one bestmeets, or acceptably meets, the selection criteria discussed earlier);receiving a message from one of the survived master UE device candidatesindicating that it is the master UE device.

In some embodiments, the method performed by the network may includesome or all of the following operations: receiving a message from aparticular UE of a plurality of UE devices, the message indicating thatthe particular UE is a master UE device; sending an acknowledgement tothe master UE device; receiving from the master UE device an indicationof D2D connections or channels and/or buffer statuses of the pluralityof UE devices; sending to the master UE device an indication of one ormore actions that are to be performed by the master UE device tocoordinate the D2D communications amongst the plurality of UE devices.

Three Specific Example Methods for Establishing the Master UE Device 104a:

FIG. 10 shows an example method of establishing the master UE device 104a in accordance with one embodiment.

In step 560, the network 106 determines that a master UE device is to beestablished, e.g. based on the need for a master UE device. Differentways in which the network 106 may make this determination are explainedearlier. For the sake of example, the network 106 may determine that amaster UE device is to be established based on an inefficiency of adirect communication between one of the plurality UE devices and thenetwork 106.

In step 562, the network 106 identifies a proper candidate master UEdevice within the plurality of UE devices 104 a-d. By “proper”candidate, it is meant a UE device that best meets or acceptably meetsthe master UE device selection criteria. Examples of master UE deviceselection criteria are discussed earlier. The proper master UE candidatemay be UE device 104 a.

In step 564, the network 106 sends to UE device 104 a a messagerequesting that UE device 104 a be a master UE device.

In step 566, the UE device 104 a accepts the request and indicates thisby transmitting a response to the network 106. In some embodiments, theUE device 104 a may be able to decline the request to be a master UEdevice. This may be due to reasons such as the following: a user of theUE device 104 a is asked for permission to be a master UE device and theuser of the UE device 104 a declines (e.g. through the user interface ofthe UE device 104 a), and/or the UE device 104 a declines based on notmeeting selection criteria (or criterion) independently evaluated by theUE device 104 a. For example, the UE device 104 a may determine that itdoes not have (or no longer has) an acceptable quality connection to thenetwork 106 and/or D2D connections with the other UE devices 104 b-d ofacceptable quality, and/or the UE device 104 a may determine that itdoes not have (or no longer has) acceptable processing, storage, and/orpower capabilities, etc., and/or that it includes suspicious softwaresuch as malware. In some embodiments, a user of the UE device 104 b-dmay also indicate through the user-interface that it is never acceptableto be a master UE device.

Assuming the UE device 104 a accepts the request to be a master UEdevice, then in step 568 the UE device 104 a sends to the network 106information relating to the status of the D2D group. Such informationmay include the buffer status of some or all of the UE devices 104 a-d(if the UE device 104 a has such information), and/or the CSI of the D2Dchannels between the UE device 104 a and the other UE devices 104 b-d.

In step 570, the network 106 confirms that the UE device 104 a will bethe master UE device and announces this to the other UEs 104 b-d.

In step 572, the network 106 receives messages from the other UE devices104 b-d indicating that they have acknowledged that the UE device 104 ais to be the master UE device.

In step 574, the master UE device 104 a assigns an internalidentification (ID) to each of the plurality of UE devices 104 a-d thatare to have their D2D communications coordinated. The internal ID may betwo bits long, with each bit permutation identifying one of the four UEdevices 104 a-d. Assigning an internal ID may save overhead compared tousing the UE device's full ID. This is because the internal ID may beshorter since it only has to distinguish between the UE devices in theD2D group (i.e. UE devices 104 a-d), not all UE devices served by thenetwork 106. Also, although “internal” ID is used, this does notnecessarily mean that it is only known to (or within) the D2D group. Forexample, the network may also know the internal IDs of some or all ofthe UE devices in the D2D group and may use the internal ID(s) to referparticular UE devices in the D2D group when communicating with the D2Dgroup.

In step 576, the UE devices 104 b-d each acknowledge reception of theirrespective ID and send their buffer status to the master UE device 104a.

In step 578, the master UE device 104 a sends a message to the network106 confirming that D2D connections are established between the masterUE device 104 a and other of the plurality of UE devices 104 b-d. Themaster UE device 104 a may also send to the network 106 the initialconfigurations between the plurality of the UE devices 104 a-d (i.e. whois currently assisting whom through D2D communications). The master UEdevice 104 a may also send to the network the buffer status of each ofthe plurality of UE devices 104 a-d, if such information has notpreviously been provided to the network 106.

In step 580, the network 106 may make a reconfiguration of D2D resourcesbetween the master UE device 104 a and the rest of the plurality of UEdevices 104 b-d and send an indication of this reconfiguration to themaster UE device 104 a. For example, the network 106 may review thequality of the D2D connections and the buffer status of each of theplurality of UE devices 104 a-d and decide who is to be a target UEdevice and who is to be a helper UE device. The network 106 may use thecriteria discussed earlier for determining target and helper UE devices.

In step 582, the network 106 may also finalize the level of cooperationof the master UE device 104 a, i.e. send to the master UE device 104 aan indication of one or more actions that are to be performed by themaster UE device 104 a to coordinate the D2D communications amongst theplurality of UE devices.

In step 584, the master UE device 104 a sends the configuration messagesto the plurality of other UE devices 104 b-d via the D2D connectionsbetween the master UE device 104 a and the plurality of UE devices 104b-d.

FIG. 11 shows an example method of establishing the master UE device 104a in accordance with another embodiment.

In step 602, the network 106 broadcasts to the plurality of UE devices104 a-d a need for a master UE device.

In step 604, the “proper” UE devices of the plurality of UE devices 104a-d announce their candidacy to the network 106. By “proper” UE deviceit is meant the UE device acceptably meets master UE device selectioncriteria. These UE devices will be referred to as the “candidate masterUE devices”.

In step 606, the network 106 verifies the suitability of the candidatemaster UE devices and notifies the candidate master UE devices.Verifying the suitability of the candidate master UE devices maycomprise the network 106 independently confirming that the master UEdevice selection criteria discussed earlier are met or are still met forthe candidate master UE devices. There could also be instances in whichthe network 106 does not want or allow a particular UE device to be amaster UE device, and if so, this would be checked against the candidatemaster UE devices. The notified candidate master UE devices will bereferred to as the “survived master UE device candidates”.

In step 608, the survived master UE device candidates then contend tobecome the master UE device. For example, one of the survived master UEdevice candidates, or another one of the plurality of UEs 104 a-d, maycollect the information from the survived master UE device candidatesrelating to the selection criteria (e.g. information that may includefactors such as quality of access to the network 106, quality of D2Dcommunication links, power availability, processing power, etc.), andthe volunteer may then select as the master UE device the survivedmaster UE device candidate that best meets (or one that acceptablymeets) the selection criteria.

In step 610, the one selected as the master UE device (i.e. UE device104 a in FIG. 1) sends a message to the network 106 requesting to be themaster UE device.

In step 612, the network 106 accepts the master UE device 104 a, andthen the network 106 (through unicast or multicast from the RRH 108 a)or the master UE device 104 a (through D2D communication) then announcesto the rest of the plurality of UE devices 104 b-d in the D2D group thatUE device 104 a is the master UE device.

FIG. 12 shows an example method of establishing the master UE device 104a in accordance with another embodiment.

In step 652, one or more of the plurality of UE devices 104 a-ddetermine that a master UE device is to be established.

In step 654, candidate master UE devices contend to become the master UEdevice, which may occur in a manner similar to (or the same as) step 608in FIG. 11.

In step 656, the selected master UE device (which is UE device 104 a inthe FIG. 1 example) accepts the nomination and sends a message to thenetwork 106 indicating that it is a master UE device.

In step 658, the network 106 sends an acknowledgement, which indicatesthat the network 106 has sanctioned the selection of the master UEdevice.

In step 660, the master UE device sends the D2D channel statutes (e.g.the level of quality of the D2D communication links between theplurality of UE devices 104 a-d, as well as the buffer status of each ofthe UE devices 104 a-d) to the network 106.

In step 662, the network 106 determines the level of D2D cooperationthat the master UE device is to coordinate by delegating or appointingsome such functions to the master UE device. This may be done by thenetwork 106 sending to at least the master UE device an indication ofone or more actions that are to be performed by the master UE device tocoordinate the D2D communications amongst the plurality of UE devices(e.g. whether the master UE device is to select target UE devices andhelper UE devices in the D2D group and/or whether the master UE deviceis to control wireless channel access for D2D communications between UEdevices, and if so then how).

In step 664, the master UE device assigns an internal ID to each of theplurality of UE devices 104 a-d that are to have their D2Dcommunications coordinated.

In step 666, the UE devices 104 b-d each acknowledge reception of theirrespective internal ID.

In step 668, the master UE device may then coordinate the D2Dcommunications amongst the plurality of UE devices 104 a-d. In someembodiments, the master UE device may keep the network 106 updated (e.g.as to target/helper configurations, for example), on a periodic orneed-to-know basis.

Other Variations and Alternative Embodiments:

In the illustrated embodiments, it has been assumed that the UE devicescommunicate wirelessly (both with a base station and directly with eachother using D2D communication). However, it could be the case that oneor more of the UE devices has a wireline connection back to the accessnetwork. For example, the master UE device may have a wirelineconnection to the access network via Ethernet. It could also be the casethat some or all of the D2D connections between the UE devices arewireline rather than wireless.

Also, it should not be assumed that the UE devices 104 a-d are allnecessarily user operated. It could be the case that one of the UEdevices 104 a-d is a “dummy” UE device, which is a UE device that doesnot belong to a particular user (i.e. customer), but instead to thenetwork. The purpose of such a dummy UE device may be to be located bythe network in coverage areas of interest and act as a helper UE devicethrough D2D communications. For example, a dummy UE device may be placedin a crowded location at an event and be designated as the master UEdevice by the network. Other “regular” UE devices (i.e. customers of thenetwork) could join a D2D group coordinated by the master (dummy) UEdevice, and by doing so become target UE devices that the master (dummy)UE device would assist using D2D communications. The master (dummy) UEdevice could also designate other UE devices in the D2D group ashelpers, if desired. However, a potential benefit of having the dummy UEdevice as the helper and master UE device is that it may be under thecomplete control of the network and so may be provisioned with suitablesecurity settings, power availability, processing capability, wirelesscommunication capability (e.g. good RF front end), etc., and may beplaced at a particular location with good access to the access network,e.g. via a wireline connection, or wirelessly via a clear line of sightto the base station. In some embodiments, the dummy UE device may be apermanent master UE device (and/or permanent helper UE device) in theD2D group.

In the embodiments above, certain operations are described as beingperformed by a D2D coordinator and a D2D participator. More generally,it will be understood that such operations are ultimately operationsperformed by the UE devices themselves. For example, when it isdescribed that the D2D coordinator 160 in FIG. 2 coordinates wirelesschannel access for the D2D communications, it will be appreciated thatit is the master UE device under the instruction of the D2D coordinatorthat ultimately performs such an operation.

With regard to the D2D coordinator mentioned above, as described earlierit may be implemented by a processor that executes instructions storedin memory. Such instructions may be provided by the network upon the UEdevice becoming designated a master UE device. In other embodiments, theD2D coordinator instructions may be stored in the UE device uponmanufacture, or downloaded at a later date, but only become operationalor activated upon the UE device being designated a master UE device. Thesame applies to the D2D participator.

In the embodiments above, some operations are performed by the accessnetwork. More generally, such operations performed on the network sidemay be performed by one or more network components. For example, if thenetwork selects a master UE device, this may be done by one or moreservers in the access network (e.g. in centralized processing system110), with the message communication with the UE devices involving oneor more base stations. In some embodiments, all of the operationsperformed by the network relating to the establishing the master UEdevice and/or D2D coordination may be performed at the base station(e.g. in RRH 108 a). However, a possible benefit of having most of theaccess network operations occur in one or more centralized processingsystems, rather than at individual base stations is that then the basestations may not each need to individually have the ability to performthe operations. This means that the base stations may be lesssophisticated (and therefore potentially less expensive), withintelligence centralized in the access network. Also, by having most ofthe access network operations occur in one or more centralizedprocessing systems, it may be easier to form and/or interact with and/orcoordinate or control a D2D group comprising UE devices that communicatewith different base stations.

In some embodiments described above, the master UE device may coordinateD2D communication between at least two UE devices in a D2D group tofacilitate wireless communication between a network (such as a basestation of the network) and at least one of the UE devices in the D2Dgroup. Examples of this described above include the master UE devicedetermining helper/target combinations/configurations, or the master UEdevice setting up (and/or helping the network set up) adecode-and-forward, aggregation or proxy service. In general,coordinating D2D communications to facilitate wireless communicationbetween the network and one or more of the UE devices may or may not beon behalf of the network. For example, the network may instruct the D2Dcoordination and/or the network may instruct the master UE device toperform a certain action or service (e.g. set up a decode-and-forward),which may result in the master UE device coordinating particular D2Dcommunications.

More generally, the master UE device does not necessarily have tocoordinate D2D communications amongst the plurality of UE devicesspecifically to facilitate a wireless communication between the networkand one or more of the UE devices. The master UE device could, forexample, coordinate a D2D communication between two UE devices for dataexchange, with or without network involvement. For example, a first UEdevice in a D2D group may want to exchange data with a second UE devicein the D2D group, and so the master UE device may coordinate this. Forexample, the master UE device may control use of the wireless channelfor the D2D transmission (that is, control when the D2D data exchangemay occur to avoid interference with the D2D transmissions of other UEdevices). In some cases, this could be done without the network evenknowing. Alternatively, the D2D coordination could be on behalf of thenetwork. For example, the network may realize that a first UE device isto transmit information to a second UE device and those two UE devicesare in the same D2D group, which is being coordinated by a master UEdevice. The network may then inform the master UE device that theinformation exchange is to occur directly. The master UE device may thencoordinate (e.g. schedule and/or control) a D2D communication betweenthe first UE device and the second UE device so that the first UE devicecan directly transmit the information from the first UE device to thesecond UE device. This is only an example. More generally, the networkcould offload tasks to the master UE device that relate tocommunications between UE devices in the group.

Another Example UE Device and Access Network:

FIG. 13 shows another example of a UE device 1004 and an access network1006. The access network 1006 includes one or more network components1002. The one or more network components 1002 may include at least oneprocessing device for performing operations of the network 1006, such asthose described above. The network components may include componentssuch as one or more severs, switches, and/or routers. The one or morenetwork components 1002 may include at least one base station, or a basestation itself may hold the one or more network components 1002. The oneor more network components 1002 may comprise a memory havinginstructions stored thereon that, when executed, cause the network 1006to perform the network operations described earlier. Shown as part ofthe one or more network components are a wireless connection establisher1008 for establishing a wireless connection with UE devices, and amaster UE device controller 1010 for controlling the master UE device tocause it to perform the operations described above.

The UE device 1004 includes one or more antennas 1011 (shown as a singleantenna in FIG. 13 for ease of illustration), processing circuitry 1012,and memory 1014. The UE device 1004 also includes communicationcircuitry 1016 to control the one or more antennas 1011 to communicatewith the access network 1006 (as at 1018) and to perform D2Dcommunications with other devices (as at 1020). The UE device 1004 alsoincludes a D2D coordinator 1022, which includes a target UE designator1024 to determine that a particular UE device (a target UE device) is tohave assistance with wireless communication between the target UE deviceand a base station. The D2D coordinator 1022 also includes a helper UEdesignator 1026 to determine whether another UE device is to assist thetarget UE device. The D2D coordinator 1022 further includes aninstructor 1028 to instruct other UE devices (and in particular theirD2D participators) to perform the D2D communications as coordinated.

The UE device 1004 also includes a D2D participator 1030 to receiveinstructions from the D2D coordinator 1022 (or from a D2D coordinator ofanother UE device), the instructions relating to coordinating the D2Dcommunications, and implementing those instructions.

Although different UE device modules are shown as separate blocks inFIG. 13 (e.g. the D2D coordinator 1022 is shown separately from the D2Dparticipator 1030), it will be appreciated that they may be implementedby the same hardware in the UE device 1004 or as one unit or set ofinstructions executed by a processing device (e.g. the processor 1012).Also, although different network modules are shown as separate blocks inFIG. 13, it will be appreciated that they may also be implemented by thesame hardware in the network 1006 or as one unit or set of instructionsexecuted by a processing device (e.g. at a server) in the network 1006.

CONCLUSION

Given all of the variations above, it will be appreciated that in oneaspect there is provided more generally a method performed by a masterUE device comprising coordinating a D2D communication between two UEdevices. FIG. 14 is one such example method, and the method of FIG. 14could be performed, for example, by a D2D coordinator in the master UEdevice. In step 1102, the UE device obtains (e.g. receives) anindication that the UE device is a master UE device that is tocoordinate D2D communications amongst a plurality of UE devices. Theplurality of UE devices includes the master UE device. The indicationreceived may be from the network, from one or more of the plurality ofdevices, or from the UE device itself (e.g. if it is the one thatultimately chooses the master UE device, and it chooses itself, or if auser of the UE device indicates that it is to be the master UE device,or if the UE device is configured upon power-up to be a master UEdevice, which may be the case if it is a “dummy” UE device).

In step 1104, the master UE device coordinates a D2D communicationbetween a first UE device of the plurality of UE devices and a second UEdevice of the plurality of UE devices. In some embodiments the first orthe second UE device may be the master UE device itself. In someembodiments, one of the first and second UE devices is a target UEdevice, and the other is a helper UE device. In some embodiments, themaster UE device may transmit an instruction to at least the first UEdevice to coordinate the D2D communication. In this case, the second UEdevice can be the master UE device or another UE device.

In some embodiments, the master UE device may determine that assistanceis to occur for a wireless communication between the network and a thirdUE device of the plurality of UE devices, where the third UE device isdifferent from the first UE device and the second UE device. The masterUE device may instruct the second UE device to use D2D communicationbetween the second UE device and the third UE device to perform theassistance. The master UE device may control wireless channel access forthe D2D communication between the second UE device and the third UEdevice to mitigate interference with the D2D communication between thesecond UE device and the first UE device.

In some embodiments, the master UE device may perform a reconfigurationafter a period of time has elapsed. For example, the master UE devicemay determine that assistance is still to occur with a wirelesscommunication between the first UE device and the network, but themaster UE device may determine that a third UE device is now to assist(instead of the second UE device). The master UE device may theninstruct the second UE device to no longer assist and instruct the thirdUE device to use D2D communication between the third UE device and thefirst UE device to assist with the wireless communication between thefirst UE device and a base station of the network.

In some embodiments, step 1104 may comprise transmitting an instructionto the second UE device that instructs the second UE device to: receivedata from a base station of the network, use the D2D communication totransmit a first portion of the data to the first UE device, and useanother D2D communication to transmit a second portion of the data to athird UE device of the plurality of UE devices.

FIG. 14 is from the perspective of the master UE device. A method isalso provided that can be performed by a first UE device, involvingreceiving an instruction from a second UE device, where the instructioncoordinates a D2D communication between the first UE device and a thirdUE device. The first UE device then communicates with the third UEdevice using the D2D communication based on the instruction. The secondUE device could be considered the master UE device and the first UEdevice a slave UE device. The first UE device may comprise a D2Dparticipator to perform the actions of the first UE device.

In some embodiments a system is also disclosed comprising: at least onebase station to wirelessly communicate with at least one of a pluralityof UE devices that are in physical proximity to each other, at least twoof the plurality of UE devices able to directly communicate with eachother using D2D communication; and processing circuitry configured toobtain and send to at least a master UE device of the plurality of UEdevices an indication of one or more actions that are to be performed bythe master UE device to coordinate D2D communications amongst theplurality of UE devices.

Through the descriptions of the preceding embodiments, it will beappreciated that the present invention may be implemented by usinghardware only or by using software and a necessary universal hardwareplatform. Based on such understandings, the technical solution of thepresent invention may be embodied in the form of a software product. Thesoftware product may be stored in a non-volatile and/or non-transitorystorage medium, which may be, for example, a CD-ROM, USB flash disk, ora removable hard disk. The software product includes a number ofinstructions that enable a computer device (e.g. processor, server, ornetwork device) to execute the methods provided in the embodiments ofthe present invention.

Although the present invention has been described with reference tospecific features and embodiments thereof, it is evident that variousmodifications and combinations can be made thereto without departingfrom the invention. The description and drawings are, accordingly, to beregarded simply as an illustration of some embodiments of the inventionas defined by the appended claims, and are contemplated to cover any andall modifications, variations, combinations or equivalents that fallwithin the scope of the present invention. Therefore, although thepresent invention and its advantages have been described in detail, itshould be understood that various changes, substitutions and alterationscan be made herein without departing from the invention as defined bythe appended claims. Moreover, the scope of the present application isnot intended to be limited to the particular embodiments of the process,machine, manufacture, composition of matter, means, methods and stepsdescribed in the specification. As one of ordinary skill in the art willreadily appreciate from the disclosure of the present invention,processes, machines, manufacture, compositions of matter, means,methods, or steps, presently existing or later to be developed, thatperform substantially the same function or achieve substantially thesame result as the corresponding embodiments described herein may beutilized according to the present invention. Accordingly, the appendedclaims are intended to include within their scope such processes,machines, manufacture, compositions of matter, means, methods, or steps.

1. A method performed by a first user equipment (UE) device comprising:receiving an instruction from a second UE device, the instructioncoordinating a D2D communication between the first UE device and a thirdUE device; and based on the instruction, communicating with the third UEdevice using the D2D communication to be assisted with wirelesscommunication.
 2. The method of claim 1, wherein communicating with thethird UE device using the D2D communication to be assisted with wirelesscommunication comprises: communicating with the third UE device usingthe D2D communication to be assisted with wireless communication betweenthe first UE device and a base station of a network.
 3. The method ofclaim 2, wherein the first UE device is a target UE device, the secondUE device is a master UE device, and the third UE device is a helper UEdevice.
 4. The method of claim 2, comprising using the D2D communicationto relay data between the first UE device and the base station.
 5. Themethod of claim 4, comprising transmitting the data from the first UEdevice to the third UE device using the D2D communication.
 6. The methodof claim 4, comprising receiving the data from the third UE device usingthe D2D communication.
 7. The method of claim 1, comprising, based onthe instruction, accessing a wireless channel during the D2Dcommunication that mitigates interference with a D2D communication of afourth UE device.
 8. The method of claim 7, comprising accessing thewireless channel using resources different from resources used by theD2D communication of the fourth UE device.
 9. The method of claim 1,wherein the D2D communication is coordinated on behalf of the network.10. The method of claim 1, wherein the first UE device, the second UEdevice, and the third UE device form a D2D group treated by the basestation as a virtual UE device.
 11. A first user equipment (UE) devicecomprising: processing circuitry configured to implement adevice-to-device (D2D) participator, the D2D participator to: receive aninstruction from a second UE device, the instruction coordinating a D2Dcommunication between the first UE device and a third UE device; andbased on the instruction, communicate with the third UE device using theD2D communication to be assisted with wireless communication.
 12. Thefirst UE device of claim 11, wherein based on the instruction the D2Dparticipator is to communicate with the third UE device using the D2Dcommunication to be assisted with wireless communication between thefirst UE device and a base station of a network.
 13. The first UE deviceof claim 12, wherein the first UE device is a target UE device, thesecond UE device is a master UE device, and the third UE device is ahelper UE device.
 14. The first UE device of claim 12, wherein the D2Dparticipator is to use the D2D communication to relay data between thefirst UE device and the base station.
 15. The first UE device of claim14, wherein the D2D participator is to transmit the data from the firstUE device to the third UE device using the D2D communication.
 16. Thefirst UE device of claim 14, wherein the D2D participator is to receivethe data from the third UE device using the D2D communication.
 17. Thefirst UE device of claim 11, wherein the D2D participator is to, basedon the instruction, access a wireless channel during the D2Dcommunication that mitigates interference with a D2D communication of afourth UE device.
 18. The first UE device of claim 11, wherein the D2Dcommunication is coordinated on behalf of the network.
 19. The first UEdevice of claim 11, wherein the first UE device, the second UE device,and the third UE device form a D2D group treated by the base station asa virtual UE device.
 20. The first UE device of claim 12, wherein theD2D participator is to transmit an indication to at least one of thesecond UE device and the network, the indication indicating that thefirst UE device requests assistance with the wireless communicationbetween the first UE device and the base station.